c# - Async/Await 和 Task<T> 不返回数据

Question

当我这样做时，它不会返回 Task<TokenModel>我的意思是这条线卡住了tokenModel = await response.Content.ReadAsAsync<TokenModel>();

Foo()
{
   var r = IsLoginOk();
}
public async Task<TokenModel> IsLoginOk()
{

  var handler = new HttpClientHandler();
  handler.UseDefaultCredentials = true;
  handler.PreAuthenticate = true;
  handler.ClientCertificateOptions = ClientCertificateOption.Automatic;

  client = new HttpClient(handler);
  client.BaseAddress = new Uri(Properties.Settings.Default.WebApiUrl);
  client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));                

  var apiAccountLogin = apiManager.ApiAccountLogin(Properties.Settings.Default.WebApiPassword, Properties.Settings.Default.WebApiUsername);

  var response = await  client.PostAsJsonAsync(apiAccountLogin.Url, apiAccountLogin.Container);

  response.EnsureSuccessStatusCode();  
  tokenModel = await response.Content.ReadAsAsync<TokenModel>();

  return tokenModel;
}

但如果我使用 void然后它工作正常

Foo()
{
     IsLoginOk();
}
public async void IsLoginOk()
{

  var handler = new HttpClientHandler();
  handler.UseDefaultCredentials = true;
  handler.PreAuthenticate = true;
  handler.ClientCertificateOptions = ClientCertificateOption.Automatic;

  client = new HttpClient(handler);
  client.BaseAddress = new Uri(Properties.Settings.Default.WebApiUrl);
  client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));                

  var apiAccountLogin = apiManager.ApiAccountLogin(Properties.Settings.Default.WebApiPassword, Properties.Settings.Default.WebApiUsername);

  var response = await  client.PostAsJsonAsync(apiAccountLogin.Url, apiAccountLogin.Container);

  response.EnsureSuccessStatusCode();  
  tokenModel = await response.Content.ReadAsAsync<TokenModel>();   
}

如我所见，我的代码类似于 Microsift 示例代码 http://msdn.microsoft.com/en-us/library/hh191443.aspx .

这是某种僵局吗？

我需要返回tokenModel。我该怎么做？ 谢谢!

Answer 1

像这样改变你的构造函数:

private Foo()
{
    // Do only synchronous initialization here
}

public static async Task<Foo> CreateAsync()
{
    var foo = new Foo();
    await foo.IsLoginOk();
    return foo;
}

您的调用方需要相应地更改。